DE102018108023A1 - Method for feeding electrical power into an electrical supply network - Google Patents

Abstract

The invention relates to a method for feeding electrical power into an electrical supply network by means of a decentralized feed unit, in particular by means of at least one wind turbine, wherein the feed unit is connected to supply a grid connection point for feeding the electrical power, the network connection point is connected directly or via a connection connection with a transformer point for transmitting the electrical power from the grid connection point to the transformer point, optionally via the terminal connection, the transformer point is connected via a transformer to a grid section for transmitting the electrical power from the transformer point via the transformer to the grid section, comprising the steps of injecting electrical real power into the electrical supply network at the grid connection point, feeding reactive electrical power into the electrical grid at the grid interconnection Vibration point, detecting a change to be made to be fed active power, changing the injected active power according to the detected, to be performed change, and limiting a change over time of the injected reactive power when changing the injected active power and / or immediately thereafter to a voltage increase at the transformer point and / or in the network section counteract, and / or temporarily activating a voltage regulation as a function of changing the injected active power to perform a voltage regulation at a reference point, in particular at the network connection point during and / or immediately after changing the injected active power to the voltage at the reference point or network connection point dynamically correct, and / or to guide along a trajectory, in particular along a ramp.

Description

The present invention relates to a method for feeding electrical power into an electrical supply network by means of a decentralized feed unit, in particular by means of at least one wind energy plant or a wind farm. Furthermore, the present invention relates to a corresponding wind turbine, which can perform such a method and the invention also relates to a wind farm with multiple wind turbines, the wind farm can perform such a method. In particular, the present invention also relates to a wind farm that can perform such a method of feeding by means of its wind turbines.

Wind turbines, wind farms or other decentralized feed-in units can nowadays not only feed into the electrical supply grid in grid parallel operation, but they can also make a contribution to controlling and stabilizing the electrical supply grid. A fundamental situation, which falls under the fact that in the case of an excess supply such decentralized feed-in units have to reduce their fed-in power to a corresponding requirement, which may, for example, come from the grid operator. In particular, wind turbines, wind farms or other decentralized feed-in units that feed by means of an inverter or inverter technology, their power very quickly, namely within a few seconds, e.g. 5 seconds or less.

Such a fast control behavior or such a fast control capability can be very advantageous for controlling the electrical supply network, but it can also undesirable effects occur. It is often the case that such a decentralized feed-in unit feeds with an at least temporarily predetermined cos (cp), which is smaller than 1 is. It is also fed reactive power. The decentralized feed unit thus feeds the desired power by feeding in a corresponding current, the current having a corresponding phase angle other than 0 with respect to the phase position of the mains voltage, that is to say the voltage in the electrical supply network. This reactive current or the corresponding reactive power is required to set a voltage level. In particular, there is a need for long connection connections between a network connection point to be fed into, and a transformer which transforms the voltage to a higher voltage level. But there are also other constellations into consideration, in which the injected reactive power or the injected reactive current affects the voltage level.

Now, if the described power reduction is performed, so the injected current is reduced. If the phase angle is unchanged, so does the cos (φ ) and thus the reactive power also decreases by reducing the injected current. This in turn can lead to an undesirable voltage change both at the grid connection point but especially at the transformer, namely in particular at a substation, although the ideal way should not be so because of cos (cp) should be adjusted so that a voltage drop across a line is compensated. However, such always suitable compensation presupposes a linear system and usually only works optimally at one point.

In principle, voltage changes, especially at the substation, can be compensated by a corresponding step transformer. The tapped transformer then changes the effective winding ratio of primary to secondary side or vice versa, in particular by mechanically changing a corresponding tap, and thus changes its transmission behavior. A voltage change can thus be compensated by appropriate adjustment of the tapped transformer. However, known step transformers are usually not able to compensate for such a rapid voltage change as can be achieved by the rapid change of the fed power by means of the decentralized feed unit. Thus, due to the lack of reactive power, there is a short-term increase in the voltage on the primary side, which can not be corrected immediately and thus can occur particularly as a voltage spike in the electrical supply network.

To counteract this, it is known to artificially slow down the control behavior of such decentralized feed-in units. Frequently, the desired power reduction is known early, because it provides, for example, to reduce noise at a certain time reducing the operation of a wind turbine. If, for example, for reasons of sound reduction at eight o'clock in the evening the operation of a wind energy plant is to be reduced, this can already be started at five minutes before eight or ten minutes before eight, when the power is then slowly reduced by means of a corresponding ramp at this earlier time so that the power actually reached the reduced value at eight o'clock in the evening. However, such a measure leads to a loss of revenue, because even earlier than necessary, a power reduction is made.

The present invention is therefore based on the object to address at least one of the above problems. In particular, a solution should be proposed in which decentralized Einspeiseeinheiten a power reduction with the least possible loss of income can be performed. At least should be proposed to previously known methods an alternative.

According to the invention, a method according to claim 1 is proposed. This method thus relates to the feeding of electrical power into an electrical supply network by means of a decentralized feed unit. The decentralized feed-in unit may in particular be a wind energy plant or several wind power plants, in particular it may form a wind farm with several wind turbines. The feed unit is connected to a grid connection point for feeding the electrical power. The grid connection point is in turn connected via a connection connection to a transformer point, namely for transmitting the electrical power from the grid connection point via the connection connection to the transformer. The transformer point is in turn connected via a transformer to a network section for transmitting the electrical power from the transformer point via the transformer to the network section. Accordingly, this topology thus includes the feed-in unit, the network connection point, the connection connection and the transformer, which is finally connected to a network section.

Presupposing this topology, active electrical power is fed into the electrical supply network at the grid connection point. In addition, reactive electric power at the grid connection point is fed into the electric grid. Furthermore, a change to be made to be fed active power is detected. It is therefore detected, for example, when the active power is to be increased or decreased in the near future or at a certain point in time. Accordingly, the injected active power is changed.

For this purpose, limiting a temporal change of the fed-in reactive power when changing the injected active power and additionally or alternatively immediately afterwards is proposed. This is proposed to counteract a voltage increase at the transformer point and / or in the network section.

In this case, a temporal change of the fed-in reactive power is deliberately proposed and this can in particular mean the specification of a ramp, that is to say a gradient, or of a limit gradient, which determines how fast the reactive power is maximally changed. However, such a limitation is not provided for the active power. The active power can therefore be reduced immediately at the time when it has to be reduced. It does not need to be reduced before. For the limitation of the temporal change of the fed-in reactive power, this is also proposed for this time or starting at this time, starting immediately or immediately thereafter.

Likewise, this can also be provided for an increase in active power. At the time when the active power is to be increased or especially to which it may be increased, it is then immediately increased to the new value, so that immediately as much active power as possible and allowed to be fed. It is thereby avoided that the active power slowed down from the same time is ramped up with a ramp, because this would yield again yield.

In addition, this also makes a comparatively fast and easy implementation possible, because in this variant, especially for the reduction of active power does not have to be planned in advance.

Preferably, the proposed limitation is performed only temporarily, namely only for the event of reducing the active power feed.

The method for limiting the reactive power gradients is particularly advantageous when the wind farm is located directly on the UW is connected and in one cos (φ) Control is located. Here it was particularly recognized that different ratios of resistance to reactance between sections in the electrical supply network on the one hand and sections in a transformer on the other hand can be expected. This makes it difficult to keep tensions constant in both sections. Here is also considered that cos (cp) can be well suited for voltage regulation for lines, whereas a voltage-dependent reactive power control (Q (U)) at the transformer, so especially at a substation, and are often better suited in the electrical supply network. It was also recognized that it should be noted that in some arrangements, a voltage-dependent reactive power control is not provided or is only complicated to implement. Then, if necessary, a voltage regulation using cos (cp) be performed. Alternatively, instead of limiting the time change of the fed-in reactive power, a temporary activation of a voltage regulation as a function of changing the injected active power is proposed. Preferably, this temporary activation is provided for a period of less than 10 minutes. This temporary voltage regulation works so that during and / or immediately after changing the fed voltage control at a reference point, in particular at the network connection point is performed to dynamically adjust the voltage at the reference point or network connection point, and / or to guide along a trajectory, in particular along a ramp. Whether to control a voltage at the grid connection point or at another reference point, such as the transformer point, may also depend on a default by the grid operator.

It is thus proposed according to this variant, a voltage regulation, in which the voltage can be controlled in particular via a reactive power setting. Controlling a voltage by adjusting a reactive power is basically known, but here it is proposed to apply such a regulation only temporarily. Only for the short event of active power reduction, this voltage regulation is proposed. Especially one can cos (cp) - There is a regulation that is suspended for the event of changing the active power.

In particular, the temporarily activated voltage regulation is active only when changing the injected active power and / or immediately thereafter. Voltage regulation operates to cause the voltage at the grid junction to be wholly or partially returned to a value that the voltage at the grid node immediately prior to changing the injected active power had changed from a value that is changed by changing the injected active power. Here it is thus particularly suggested to reduce the tension to the old value. This should be done dynamically to avoid signal peaks. For example. For this, a vibration-free behavior of a delay element of second order can be specified. Preferably, the behavior of how the voltage is conducted, namely to be particularly attributed, is fixed by a trajectory. Thus, a voltage curve is fixed and the behavior can be kotrolliert. Signal peaks are avoided.

The temporarily activated voltage regulation is preferably carried out in particular if the network connection point is directly connected to a transformer point, ie if there is no connection connection or the connection has no or no significant influence on the reactive power voltage behavior. For this purpose, it has been particularly recognized that there is no influence by a connection connection and therefore an immediate voltage regulation to the reference point can be advantageous.

The limiting of the time-dependent change of the fed-in reactive power preferably takes place in such a way that the fed-in reactive power is changed according to a change function, in particular according to a ramp with a slope limited in magnitude. It is thus given a ramp for changing the reactive power, thereby avoiding a reactive power jump. The steepness of this ramp and thus the speed of the change of the reactive power is preferably given as a limit, so that it is not exceeded in any case. A lower slope may be considered.

In addition or as an alternative, the limiting takes place in such a way that a gradient limit value is specified for the reactive power fed in, which predetermines a maximum temporal change of the fed reactive power, in particular such that the fed reactive power is changed with a time gradient which corresponds to the magnitude Does not exceed the gradient limit. As a result, a maximum rate of change, which can not be exceeded, is predetermined by such a gradient limit value. A weaker change is allowed. As a result, the change in the reactive power is basically arbitrary, but is limited in terms of excessive changes in time.

According to one embodiment, it is proposed that the transformer has a primary side to which the transformer point is connected, that the transformer has a secondary side to which the network section is connected, and that the transformer is designed as a step transformer and a transmission ratio from the primary side to the secondary side can adjust, thereby controlling a voltage level at the transformer point. Thus, for this embodiment is based on such a step transformer and it is proposed that the limitation of the change over time of the injected reactive power is such that a resulting from the change in the fed reactive power voltage change at the transformer point or on the primary side is so slow that the tapped transformer she can control.

Here it was particularly recognized that the reactive power can also influence the voltage level on the primary side of the transformer. Although a step transformer used there can compensate for a voltage change, so that a voltage change on the primary side does not lead or reduces to a corresponding voltage change on the secondary side, but this can only be done comparatively slowly.

Thus, it was recognized to adapt the limitation of the temporal change of the input reactive power to the dynamics of the tapped transformer. In particular, by a correspondingly flat ramp for controlling the change in the reactive power can be achieved accordingly that the voltage on the primary side of the tapped transformer changes only slowly. In this case, it is basically proposed to provide the limitation of the time change of the fed-in reactive power only if a change to be made in the active power to be fed has been detected, that is to say if intentional gradients of the active power or reactive power are present. The limitation is therefore only temporary and should not limit any changes.

Preferably, it is provided here that a ramp function is specified for the change of the reactive power, which predefines a change from a reactive power initial value to a reactive power end value and for this provides at least a duration of one minute, in particular of at least two minutes and preferably of at least five minutes. Thus, the rate of change of the reactive power is significantly limited and basically adapted to a dynamic of the tapped transformer. It should be noted that a change in reactive power, if not limited as proposed, can be accomplished in a few seconds or even faster by a feed unit using an inverter. It is therefore proposed a slowdown many times over the technical possibilities of an inverter.

In particular, it is proposed that despite limitation of the time change of the fed reactive power for the fed active power no limitation of a temporal change is provided. It is therefore expressly proposed to provide different dynamics for the active power and the reactive power, namely for the reactive power a very slow dynamics and for the active power a fast or unlimited dynamics. The change in the active power is then only technically conditioned by the decentralized feed-in unit and in particular by its inverter. But even a change in power extraction from the wind in a wind turbine can be performed in modern pitch-controlled wind turbines within a few seconds. Such a speed of change of the active power should also be allowed here, while the reactive power is limited in its temporal change, namely, in particular is very much limited compared to the said rate of change of active power.

According to one embodiment, it is proposed that when changing the fed active power and / or immediately thereafter a voltage regulation at the network connection point or at another point in the network, in particular the secondary side of the transformer is performed to the voltage at this point, thus also as a control point may be designated to balance to a value, or to guide along a trajectory, in particular along a ramp.

It is thus proposed in particular that the change in the reactive power is temporarily incorporated into a control loop. This control loop detects the voltage at the network connection point or another point or control point in the network, which could also be done indirectly via a measurement filter or state observer, but preferably directly via a measurement, and returns this so detected voltage at the network connection point for the scheme. In particular, a setpoint / actual value comparison is then carried out in which a desired voltage value is compared with an actual voltage value, namely with the detected voltage, and this control deviation is then used as an input variable for reactive power regulation. The reactive power is thus adjusted as a function of such a voltage deviation. This can also be used to control the voltage along a trajectory, namely by specifying instead of a constant voltage value a voltage curve as a voltage setpoint and with this the described comparison with the detected voltage, ie with the actual voltage, is then performed.

In particular, by such a guidance of the voltage along a trajectory, a desired voltage profile can be predetermined and this can also be done so that the voltage waveform leads to a voltage change not only at the grid connection point, but also at the primary side of the transformer, ie at the transformer point, the step transformer can compensate. Thus, excessive voltage changes are avoided by a targeted regulation.

According to one embodiment it is provided that for the supply of electrical reactive power, a power factor control is provided, which can also be referred to as cos (φ) control. In such a power factor control, the injected reactive power is adjusted depending on the injected active power so that a predetermined power factor, which also as cos (cp) respectively. cos is designated results. In this case, the fed reactive power is initially changed simultaneously with the change in the active power fed so that the power factor remains unchanged. But then it becomes a new value for the power factor as a function of a voltage which changes as a result of the change in the active power and reactive power at the network connection point. The new value for the power factor can, however, also be predefined as a function of a changing voltage at the network connection point which is to be expected as a consequence of the change in the active power and reactive power. In other words, a change in the active power and reactive power leads to a change in the voltage. This can be counteracted by changing the power factor. This can either be done so that the immediately resulting voltage change is converted as soon as possible into a modified power factor, thereby counteracting the voltage, or this voltage change can already be anticipated.

Due to the topology or previous measurements, it may be well known how the voltage at the grid junction will change in response to the change in real power and reactive power. Insofar as such a change in the voltage is not desired, this can be counteracted by a corresponding change in the power factor, in particular so that the power factor is changed right at the start of the change in active power, so that the reactive power does not even change so much that it is undesirable high voltage change at the network connection point or another point or control point in the network occurs.

In any case, in both cases, the result will be a modified power factor, which is changed from the described initial situation. It is now proposed to return this changed power factor to the former power factor, namely the power factor then and still provided. The power factor has therefore been changed only temporarily to counteract the change in the voltage at the network connection point, or another point or control point in the network. The power factor is thus fed back again, wherein the feedback is delayed and also or alternatively carried out via a time function.

It is also proposed here that the power factor is not due to a step function, which can also be referred to as a step function, but gradually. This can take place via different delays, such as, for example, via a PT1 behavior, to name just one variant. However, it can also be traced back via a corresponding time function and a simple time function is a corresponding ramp which starts at the temporarily modified power factor and ends at the previous, ie predetermined, power factor. Instead of a ramp but also other functions come into consideration, which should as possible but have no or at most small jumps.

This is thus based on a solution for a conventional feed using a power factor control. Such a power factor control basically provides to maintain a fixed power factor and always change the reactive power according to this power factor with active power changes. For this control concept, it is proposed to keep it as unchanged as possible, but to temporarily change the power factor for the described critical case of the undesired strong change in the voltage at the network connection point. Thus, only the described power factor change needs to be made and the overall implemented power factor control can be maintained.

• - für das Einspeisen elektrischer Blindleistung eine Leistungsfaktorregelung (cos(φ)-Regelung) vorgesehen ist, bei der die eingespeiste Blindleistung in Abhängigkeit der eingespeisten Wirkleistung so eingestellt wird, dass sich ein vorgegebener Leistungsfaktor (cos(cp)) ergibt, wobei
• - bei der Veränderung der eingespeisten Wirkleistung diese entlang einer Rampe oder Trajektorie verändert wird. Diese Veränderung wird insbesondere in einer Zeit von weniger als einer Minute, insbesondere im Bereich von 10 Sekunden bis 40 Sekunden durchgeführt.

According to one embodiment, it is proposed that

• - For the supply of electrical reactive power, a power factor control (cos (φ) control) is provided in which the injected reactive power is adjusted depending on the injected active power so that a predetermined power factor (Cos (cp)) yields, where
• - When changing the injected active power this is changed along a ramp or trajectory. This change is carried out in particular in a time of less than one minute, in particular in the range of 10 seconds to 40 seconds.

• - beim Verändern der eingespeisten Wirkleistung entlang der Rampe oder Trajektorie eine Spannungsregelung verwendet wird, um die Spannung an dem Referenzpunkt konstant zu halten, zumindest um einer Spannungsveränderung durch das Verändern der eingespeisten Wirkleistung entgegenzuwirken, wobei die Spannungsregelung dazu die Blindleistung einstellt und die Leistungsfaktorregelung (cos(cp)-Regelung) während dieser Spannungsregelung deaktiviert ist,
• - nach der Veränderung der eingespeisten Wirkleistung ein Blindleistungswert, der aus der Spannungsregelung resultiert, auf einen neuen Blindleistungswert geführt wird, der sich durch die deaktivierte Leistungsfaktorregelung (cos(cp)-Regelung) ergäbe, wobei
• - der Blindleistungswert insbesondere über eine Rampe und/oder Trajektorie auf den neuen Blindleistungswert geführt wird. Für diese Rückführung ist vorzugsweise ein Zeitraum von 2 Minuten bis 10 Minuten vorgesehen, insbesondere ein Zeitraum von 3 bis 7 Minuten, Anschließend wird dann die deaktivierte Leistungsfaktorregelung (cos(cp)-Regelung) wieder aktiviert, nämlich sobald der Blindleistungswert den neuen Blindleistungswert erreicht hat.

It is further suggested that

• - When changing the injected active power along the ramp or trajectory voltage regulation is used to keep the voltage at the reference point constant, at least to counteract a voltage change by changing the injected active power, the voltage control to the reactive power sets and the power factor control (cos (cp) control) is deactivated during this voltage regulation,
• - After the change in the injected active power, a reactive power value resulting from the voltage regulation, is led to a new reactive power value, which would result from the deactivated power factor control (cos (cp) control),
• - The reactive power value is guided in particular via a ramp and / or trajectory to the new reactive power value. For this Feedback is preferably a period of 2 minutes to 10 minutes provided, in particular a period of 3 to 7 minutes, then then the deactivated power factor control (cos (cp) control) is activated again, as soon as the reactive power value has reached the new reactive power value.

Accordingly, here too, first of all a regular feed with active power feed ( P ) and reactive power setting ( Q ) according to a set power factor cos (cp) went out. Then there is an active power ramp with temporarily activated voltage regulation. This results in the end of a modified Q-value, which is chosen so or adjusts itself by the voltage control that, if possible, the voltage is held substantially at the old value.

Then, the difference between a reactive power setpoint (Q setpoint) corresponding to the power factor control (cos (cp) control) and the current reactive power value (Q value) is determined according to the voltage regulation. This is followed by a slow ramp-down of the reactive power value (Q value) to the value in accordance with the power factor control (cos (cp) control). This is done so that there is only a continuous change in voltage. A step plate. So a variable transformer, then can respond to this continuous voltage change.

Preferably, it is proposed that the changing of the injected active power is carried out via an active power jump, although, on the other hand, the changing of the reactive power is performed via a time function, in particular via a ramp function. It is thereby achieved in particular that an active power change can be carried out as quickly as possible in order to avoid power losses. Unwanted voltage jumps or otherwise unwanted voltage changes, especially at the grid connection point or other point in the electrical supply network, but can be avoided by the non-jump adjustment of reactive power. The choice of the point at which unwanted voltage jumps or otherwise undesirable voltage changes are avoided, may depend on a network operator by, for example, it pretends.

Preferably, the limitation of the change of the input reactive power depends on the type and / or size of the connection connection. It was particularly recognized here that the connection connection, that is to say in particular a line between the network connection point and the transformer point, that is to say the transformer, can vary greatly in terms of its impedance. There may be topologies with large and small impedances, but in particular the reactance, ie the reactive component of the impedance, can be very different. Depending on the type of line, the reactance, ie the reactive component, can be as large as the ohmic resistance, ie the active component, the impedance, or many times greater than the ohmic resistance. This has particular effects on reactive power-dependent voltages or on how reactive power changes change the voltage. This is preferably taken into account when limiting the time change of the fed-in reactive power.

• - die Windenergieanlage zum Einspeisen der elektrischen Leistung an einen Netzverknüpfungspunkt angeschlossen ist,
• - der Netzverknüpfungspunkt über eine Anschlussverbindung mit einem Transformatorpunkt verbunden ist, zum Übertragen der elektrischen Leistung von dem Netzverknüpfungspunkt über die Anschlussverbindung an den Transformatorpunkt,
• - der Transformatorpunkt über einen Transformator mit einem Netzabschnitt verbunden ist, zum Übertragen der elektrischen Leistung von dem Transformatorpunkt über den Transformator zum Netzabschnitt, und die Windenergieanlage umfasst
• - einen Wechselrichter zum Einspeisen elektrischer Wirkleistung in das elektrische Versorgungsnetz an dem Netzverknüpfungspunkt,
• - eine Wechselrichtersteuerung zum Steuern eines Einspeisens elektrischer Blindleistung in das elektrische Versorgungsnetz an dem Netzverknüpfungspunkt, eine Eingabeschnittstelle zum Erfassen einer durchzuführenden Änderung der einzuspeisenden Wirkleistung, wobei
• - die Wechselrichtersteuerung vorbereitet ist zum Verändern der eingespeisten Wirkleistung entsprechend der erfassten, durchzuführenden Änderung, und wobei
• - die Wechselrichtersteuerung vorbereitet ist zum Begrenzen einer zeitlichen Veränderung der eingespeisten Blindleistung beim Verändern der eingespeisten Wirkleistung und/oder unmittelbar danach, um einer Spannungserhöhung am Transformatorpunkt und/oder im Netzabschnitt entgegen zu wirken, und/oder
• - die Wechselrichtersteuerung dazu vorbereitet ist, ein temporäres Aktivieren einer Spannungsregelung in Abhängigkeit des Veränderns der eingespeisten Wirkleistung durchzuführen, um während und/oder unmittelbar nach dem Verändern der eingespeisten Wirkleistung eine Spannungsregelung an einem Referenzpunkt, insbesondere am Netzverknüpfungspunkt durchzuführen, um die Spannung am Referenzpunkt bzw. Netzverknüpfungspunkt dynamisch auszuregeln, und/oder entlang einer Trajektorie zu führen, insbesondere entlang einer Rampe.

According to the invention, a wind turbine is also proposed for feeding electrical power into an electrical supply network, wherein

• the wind energy installation is connected to a grid connection point for feeding in the electrical power,
• the network connection point is connected to a transformer point via a connection connection, for transmitting the electrical power from the network connection point via the connection connection to the transformer point,
• - The transformer point is connected via a transformer to a network section, for transmitting the electrical power from the transformer point via the transformer to the network section, and the wind turbine comprises
• an inverter for feeding active electrical power into the electrical supply network at the grid connection point,
• an inverter controller for controlling a supply of reactive electric power to the electric utility network at the grid connection point, an input interface for detecting a change in the active power to be fed in, wherein
• - The inverter control is prepared for changing the fed active power according to the detected, to be performed change, and wherein
• - The inverter control is prepared for limiting a change over time of the supplied reactive power when changing the injected active power and / or immediately thereafter to counteract a voltage increase at the transformer point and / or in the network section, and / or
• the inverter control is prepared to temporarily activate a voltage regulation as a function of changing the voltage to perform fed active power to perform during and / or immediately after changing the injected active power voltage regulation at a reference point, in particular at the network connection point to dynamically adjust the voltage at the reference point or network connection point, and / or along a trajectory, in particular along a Ramp.

In particular, the feeding is carried out by means of an inverter, which receives its power from a generator. The inverter can be controlled by the inverter control and also other steps can be controlled. In particular, such an inverter controller can control the changing of the injected active power according to the detected change to be made, and it can also limit the time variation of the supplied reactive power. In particular, the inverter controller can implement corresponding control control algorithms for each and generate resulting setpoint values for the active power, reactive power and / or the power factor or phase angle. These setpoints can then be converted by the inverter accordingly. In this case, a desired value for a current to be fed can also be specified.

Preferably, the wind turbine is prepared to perform a method according to at least one of the embodiments described above. For this purpose, corresponding algorithms can be implemented in the inverter control or another control unit, preferably at least one voltage sensor is provided to detect a voltage at the network connection point or another point in the network.

According to the invention, a wind farm comprising several wind turbines is also proposed which comprises at least one wind energy installation according to the invention, and / or at least one method according to one of the embodiments described above, which relate to a method for feeding. For this purpose, the corresponding method can be implemented in a central control unit of the wind farm or is carried out individually by the wind energy plant.

• - eine dezentrale Einspeiseeinheit, insbesondere eine Windenergieanlage,
• - einen Netzverknüpfungspunkt,
• - einen Transformator mit einem Transformatorpunkt, wobei
• - die Einspeiseeinheit zum Einspeisen der elektrischen Leistung an den Netzverknüpfungspunkt angeschlossen ist,
• - der Netzverknüpfungspunkt unmittelbar oder über die Anschlussverbindung mit dem Transformatorpunkt verbunden ist, zum Übertragen der elektrischen Leistung von dem Netzverknüpfungspunkt über die Anschlussverbindung an den Transformatorpunkt,
• - der Transformatorpunkt über den Transformator mit einem Netzabschnitt verbunden ist, zum Übertragen der elektrischen Leistung von dem Transformatorpunkt über den Transformator zum Netzabschnitt, und die Einspeiseanordnung umfasst
• - einen Wechselrichter zum Einspeisen elektrischer Wirkleistung in das elektrische Versorgungsnetz an dem Netzverknüpfungspunkt,
• - eine Wechselrichtersteuerung zum Steuern eines Einspeisens elektrischer Blindleistung in das elektrische Versorgungsnetz an dem Netzverknüpfungspunkt, eine Eingabeschnittstelle zum Erfassen einer durchzuführenden Änderung der einzuspeisenden Wirkleistung, wobei
• - die Wechselrichtersteuerung vorbereitet ist zum Verändern der eingespeisten Wirkleistung entsprechend der erfassten, durchzuführenden Änderung, und wobei
• - die Wechselrichtersteuerung vorbereitet ist zum Begrenzen einer zeitlichen Veränderung der eingespeisten Blindleistung beim Verändern der eingespeisten Wirkleistung und/oder unmittelbar danach, um einer Spannungserhöhung am Transformatorpunkt und/oder im Netzabschnitt entgegen zu wirken und/oder
• - die Wechselrichtersteuerung dazu vorbereitet ist, ein temporäres Aktivieren einer Spannungsregelung in Abhängigkeit des Veränderns der eingespeisten Wirkleistung durchzuführen, um während und/oder unmittelbar nach dem Verändern der eingespeisten Wirkleistung eine Spannungsregelung an einem Referenzpunkt, insbesondere am Netzverknüpfungspunkt durchzuführen, um die Spannung am Referenzpunkt bzw. Netzverknüpfungspunkt dynamisch auszuregeln, und/oder entlang einer Trajektorie zu führen, insbesondere entlang einer Rampe.

According to the invention, a feed arrangement for feeding electrical power into an electrical supply network is proposed, comprising

• a decentralized supply unit, in particular a wind turbine,
• a network connection point,
• - A transformer with a transformer point, where
• the feed unit is connected to the grid connection point for feeding in the electrical power,
• the network connection point is connected directly or via the connection connection to the transformer point, for transmitting the electrical power from the network connection point via the connection connection to the transformer point,
• - The transformer point is connected via the transformer to a network section, for transmitting the electrical power from the transformer point via the transformer to the network section, and the feed arrangement comprises
• an inverter for feeding active electrical power into the electrical supply network at the grid connection point,
• an inverter controller for controlling a supply of reactive electric power to the electric utility network at the grid connection point, an input interface for detecting a change in the active power to be fed in, wherein
• - The inverter control is prepared for changing the fed active power according to the detected, to be performed change, and wherein
• - The inverter control is prepared for limiting a change over time of the supplied reactive power when changing the injected active power and / or immediately thereafter to counteract a voltage increase at the transformer point and / or in the network section and / or
• - The inverter control is prepared to perform a temporary activation of a voltage control in response to changing the injected active power to perform during and / or immediately after changing the injected active power a voltage control at a reference point, in particular at the grid connection point to the voltage at the reference point or To dynamically balance and / or guide along a trajectory, in particular along a ramp.

The feed arrangement thus has at least one decentralized feed-in unit, in particular a wind power plant, and additionally also a grid connection point, a connection connection a transformer with a transformer point. Otherwise, their results Design and operation according to the embodiments described above.

The feed arrangement thus preferably has a wind power plant according to at least one embodiment of a wind energy plant described above. Additionally or alternatively, it has a wind farm according to at least one embodiment of a wind farm described above. Additionally or alternatively, the feed arrangement is prepared to carry out a method according to at least one embodiment of a method described above.

The effect and the advantages arise accordingly from the respective explanations of the respective embodiments mutatis mutandis.

• 1 zeigt eine Windenergieanlage in einer perspektivischen Darstellung.
• 2 zeigt einen Windpark in einer schematischen Darstellung.
• 3 zeigt eine Einspeiseanordnung in einer schematischen Darstellung.
• 4 zeigt ein Ersatzschaltbild zur Einspeiseanordnung der 3.
• 5 zeigt ein Diagramm einer Einspeiseänderung gemäß dem Stand der Technik.
• 6 zeigt ein weiteres Diagramm einer Einspeiseänderung.
• 7 zeigt ein Diagramm einer Einspeiseänderung gemäß einer vorgeschlagenen Ausführungsform.
• 8 zeigt ein Diagramm einer Einspeiseänderung gemäß einer weiteren Ausführungsform.
• 9 zeigt ein Diagramm einer Einspeiseänderung gemäß einer noch weiteren Ausfü h ru ngsform.

The invention will now be described by way of example with reference to embodiments with reference to the accompanying drawings.

• 1 shows a wind turbine in a perspective view.
• 2 shows a wind farm in a schematic representation.
• 3 shows a feed arrangement in a schematic representation.
• 4 shows an equivalent circuit diagram to the feed arrangement of 3 ,
• 5 shows a diagram of a feed change according to the prior art.
• 6 shows another diagram of a feed change.
• 7 shows a diagram of a feed change according to a proposed embodiment.
• 8th shows a diagram of a feed change according to another embodiment.
• 9 FIG. 12 is a diagram of a feed change according to yet another embodiment. FIG.

1 shows a wind turbine 100 with a tower 102 and a gondola 104 , At the gondola 104 is a rotor 106 with three rotor blades 108 and a spinner 110 arranged. The rotor 106 is set in operation by the wind in a rotary motion and thereby drives a generator in the nacelle 104 at. For feeding is an inverter 130 provided by an inverter control 132 can be controlled. The inverter control is also provided with an input interface 134 provided over the setpoints, especially an active power setpoint Ps can be entered.

2 shows a wind farm 112 with exemplary three wind turbines 100 that can be the same or different. The three wind turbines 100 are thus representative of basically any number of wind turbines in a wind farm 112 , The wind turbines 100 put their power, namely in particular the electricity generated via an electric parking network 114 ready. In this case, the currents or outputs of the individual wind turbines are generated 100 and mostly is a transformer 116 provided that transforms the voltage in the park, then at the feed point 118 who is also generally considered PCC is referred to in the supply network 120 feed. It is also a stage transformer 124 provided by a connection 122 with the entry point 118 connected, which can also be referred to as a network connection point. About the step transformer 124 the voltage will continue to be on the voltage in the supply network 120 highly transformed. The wind turbines 100 can like in 1 be shown, including inverters 130 and inverter control 132 with input interface 134 , But it can also be one for the park 112 be provided central control.

2 is only a simplified representation of a wind farm 112 which does not show control, for example, although of course a controller is present. Also, for example, the parking network 114 be designed differently, for example, by a transformer at the output of each wind turbine 100 is present, to name just another embodiment.

The feed arrangement 300 of the 3 has a wind farm 302 as a decentralized feed-in unit. This wind farm 302 is at a network junction point 304 connected and via a connection cable 306 , which forms a connection here, via a busbar 308 with a transformer point 310 connected. The busbar 308 can also be part of the transformer point 310 be viewed because the busbars 308 basically the connection hardware of the transformer point 310 forms. Thus, the connection cable 306 with the transformer point 310 connected.

The connection cable 306 Here, for example, it is designed for a voltage level of 20kV and this voltage can be supplied via a transformer 312 be transformed to a higher voltage, which is exemplified here 110kV and the voltage level of the network section 314 forms. Accordingly, the transformer 312 with the network section 314 connected. The transformer has a primary side here 316 and a secondary side 318 on.

Illustrating is parallel to the connection cable 306 a parallel strand 320 illustratively also showing the network connection point 304 with the busbar 308 or the transformer point 310 can connect if a likewise illustrative disconnect switch 322 closed is. Also illustrative are various consumers, for example, industrial consumers 324 and not industrial consumers 326 in the area of the connection cable 306 or the parallel strand 320 indicated, which can be connected there each. Despite the same reference numerals 324 respectively. 326 Nevertheless, these consumers can be different.

For this feeder arrangement shown 300 Now a method is provided in which the wind farm as a representative decentralized feed unit both active power and reactive power at the grid connection point 304 feeds. The fed active power can then be changed according to a corresponding specification, ie a change to be made. For example. it can be halved with appropriate specification. At the same time a temporal change of the fed reactive power is limited. This is done so that a voltage increase at the transformer 312 , namely at the transformer point 310 and / or at the network connection point 304 counteracted. This does not have to mean that a voltage increase is excluded here, but it is at least reduced compared to a voltage increase in magnitude, which would result without such a temporal change of the input reactive power.

In this way, it can be achieved that voltage jumps at the transformer and / or at the network connection point are limited in the case of an unfavorable or even incorrect parameterization of a cos (cp) -control or -control. Such an unfavorable parameterization may, for example, occur depending on a reactive power budget, for example, if a reactive power feed or effect is misjudged, or reactive power can not be delivered as intended.

In the case of correct, optimal or ideal parameterization, the cos (φ) at the network connection point would be set so that the voltage would scarcely change given a power change. In the event that a wind farm immediately adjacent to a busbar like that of the busbar 310 is connected, would ideally assume a purely inductive character and cos (cp) parameterized to one. However, there are regular deviations from this ideal state, which are taken into account here.

The 4 now shows an equivalent circuit diagram for the feed arrangement example 300 of the 3 or for a part of it. The equivalent circuit diagram of 4 basically always assumes that the circuit breaker 322 as in 3 shown is open. If it were closed, but would give a very similar equivalent circuit diagram, but with other concrete values, namely with other concrete impedances or at least one other impedance.

According to shows 4 first again the wind farm 302 which is in the network link point 304 feeds. The connection section to the busbar 308 and thus to the transformer point 310 has a connection impedance 406 on. This connection impedance 406 is as impedance Z ₃ designated. Here very concrete values are given, to which also the results of the diagrams shown below refer. However, these values mentioned and explained below are given by way of example only and may have both small and large deviations therefrom.

In any case, the exemplary connection impedance 406 an ohmic part, ie active part of 5,78Ω on and a reactance value, ie reactive component of 4,83Ω , As already explained, it does not depend on the exact values, for the connection impedance 406 But it should be noted that it has about the same amount of active and reactive components here. An active current and a reactive current in each case the same amplitude would thus at this connection impedance 406 lead to about the same voltage drops.

To the busbar 308 or the transformer point is followed by a transformer impedance 412 and a network impedance 414 of a superposed network. The network or the network section 314 can on the primary side 316 of the transformer 312 transformed as a voltage source 415 be considered with the voltage level 20kV. Both the transformer impedance 412 as well as the network impedance 414 are thus impedances that on the low voltage side, so the voltage side of the primary side 316 of the transformer 312 are transformed. Here is the transformer impedance 412 correspondingly for a transformed impedance of the transformer. The network impedance 414 stands for a transformed impedance of the network section 314 ,

Here, too, exemplary values are given, which were taken into account below, but which may also be different. In any case, the values of the transformer impedance are 412 0,14Ω for the ohmic component and 3Ω for the component of the reactance. At the network impedance 414 is an ohmic portion of 0,07Ω and a proportion of the reactance of 0.4 Ω in front. It can be seen that especially the transformer impedance 412 a much greater reactance value than that Has value of the ohmic resistance. Here is about a factor of 20 between the two shares. It can thus be seen that a change in the reactive current through this transformer impedance 412 a significantly higher voltage change results than a change in the active current. Accordingly, it may be particularly, but not exclusively, the transformer impedance 412 come to an undesirable voltage change when active and reactive power coming from the wind farm 302 be fed in the same measure be changed.

In principle, the injection of active and reactive power, which also includes the negative feed of reactive power, can be selected so that - clearly speaking - the reactive power counteracts a voltage increase by the active power. This applies in any case to the network connection point if a connection connection dominating here, ie a dominant cable impedance of the connection connection, is present. But if both values are changed equally, this can lead to a new situation at another point where this compensation no longer exists. This has been particularly recognized as a problem in wind farms, in which the network connection point are connected directly or with little dominant connection connection to a transformer, in particular a substation. This is especially true if the grid connection point is directly connected to the transformer, or even in the substation and if the wind farms are in a cos (φ) control. This may, for example, be the case if a corresponding control of the reactive power budget requires this. It was recognized that in such a case, the active current hardly acts lift, but the reactive current has a voltage lowering effect. If, in such a case, the reactive current is missing, there is a sudden increase in the voltage during the power increase.

The following diagrams illustrate different ways to change the active and reactive power and show the resulting potential effects.

5 shows a diagram showing a known type of variation.

In the diagram of 5 Power and voltage curves are plotted over time. It is initially assumed there from a stable feed-in situation, until the time t _R an active power reduction is specified and then implemented. In that regard, the diagram shows a fed Parkwirkleistung P _WEA , the example of which at the time of reduction t _R is reduced by example 10MW to about 3MW. The reduction is basically instantaneous, so the graph of the 5 For example, a stepped course for the reduction of active power P _WEA shows. Due to a fixed phase angle, the injected reactive power Q _WEA also at the time of reduction t _R reduced, namely basically steplike. The diagram then shows deviations between the active power P _WEA and the reactive power Q _WEA , which are partly related to the representation and are less important here. In any case, the fed reactive power Q _WEA with the active power together quickly reduced.

As a result or as related consequences, both the voltage can U _NVP at the network connection point 304 , as well as the voltage Uss at the busbar 308 which in turn reduces the voltage at the transformer point 310 corresponds, change.

It can be seen that the reduction of active power P _WEA and the reactive power Q _WEA to a reduction of tension U _NVP at the network connection point. This is especially related to the connection impedance 406 has a higher ohmic component compared to the reactive power component. This results in a reduction of the active power to a voltage reduction, which counteracts the simultaneous reduction of reactive power. But since the reactance component of the connection impedance 406 is smaller than the ohmic component, the simultaneous reduction of reactive power can not completely counteract the voltage reduction due to the reduction in active power. At a phase angle optimally set for this network link point, however, the voltage change at the network link point (NVP) would be minimal.

The voltage Uss at the busbar is a bit different because of the transformer impedance 412 but also, albeit slightly lower, the network impedance or transformed network impedance 414 each have a significantly higher reactance component compared to the ohmic component. There, the voltage-boosting effect due to the reactive power reduction is stronger than the voltage-lowering effect due to the reduction in active power. For this reason, the voltage at the busbar Uss increases at the time of reduction t _R undesirable.

A particular problem here is that this voltage increase is accompanied so rapidly, namely directly with the active power reduction and reactive power reduction, that a tapped transformer can not compensate this fast enough. Especially the transformer 312 can be designed here as a tapped transformer to a slow voltage increase at the transformer point 310 counteract.

The first countermeasure proposed in the prior art is the active power P _WEA slowly reduce, so that also the reactive power Q _WEA slowly reduced. Is in 6 shown.

Out 6 is in the diagram but to recognize that to achieve a target value for the active power to be reduced P _WEA at the time of reduction t _R to achieve, the reduction must start earlier. For this, the reduction of the active power is already started at the preliminary time point tv. In fact, this ensures that the voltage at the grid connection point U _NVP as well as the voltage at the busbar accordingly changed slowly. Here is a period of 400 seconds from the advance time tv to the reduction time t _R intended. The changes in the voltage shown, in particular the change in the voltage at the busbar Uss shown is then sufficiently slow that a tapped transformer can compensate for this voltage change. However, this is achieved with too early a reduction in power, which begins 6.5 minutes too early with the 400 seconds given by way of example and thus leads to a loss. This loss can be due to the indicated energy triangle 630 be illustrated.

To avoid this, according to one embodiment, a slow reduction in reactive power is suggested, such as 7 clarified.

According to this embodiment, in the diagram of 7 Thus, it is proposed that at the time of reduction t _R the active power fed in by the wind farm P _WEA is gradually reduced, while the fed reactive power Q _WEA but initially kept constant. This leads to a larger inductive cos (cp). The voltage at the network connection point U _NVP breaks thereby at the net connection point 304 strong.

Anyway breaks the voltage Uss at the busbar 308 only a little, because it depends on the design of the transformer impedance 412 and transformed network impedance 414 only slightly from the active power and thus experiences by the step-shaped reduction of the injected active power P _WEA only a very small break.

The injected reactive power Q _WEA but then from the time of reduction t _R lowered according to a ramp or linear function. Both the tension U _NVP at the network connection point 304 , as well as the voltage Uss at the busbar 308 thereby increasing gradually.

The strong break in tension U _NVP at the network connection point 304 is acceptable and may be due to the gradual change in reactive power Q _WEA from the time of reduction t _R be increased again. Their course represents for the electrical supply network, especially the network section 314 , no special problem. The increase of the voltage Uss at the busbar 308 but is so slow that a tapped transformer can compensate for this change. This results in only a small effect on the electrical supply network, especially the voltage at the transformer point 310 be kept substantially constant.

Basically, here too, the gradual change in reactive power achieves a gradual change in the voltage Uss across the busbar, which can be compensated by a tapped transformer. However, the solution proposed here creates, nevertheless, that the active power only gradually at the time of reduction t _R is reduced and thus no loss of income occurs. Here it was also particularly recognized that the voltage reactions at the network connection point 304 on the one hand and a busbar 308 on the other hand are different on active power changes and reactive power changes. Particularly when the grid connection point is directly connected to the busbar and the wind farm uses or is in cos (cp) control, there are advantages in said method. This has been deliberately taken into account and thus particularly a solution proposed that avoids an abrupt large voltage jump on the busbar and then a corresponding voltage jump on the secondary side 316 of the transformer 312 avoids. Because the grid voltage can be considered approximately constant, unwanted voltage differences between the primary and secondary sides of the transformer are avoided.

8th shows a variant of the variant of 7 is similar. Again, the reduction time t _R the active power P _WEA reduced. The reactive power Q _WEA However, here is also the reduction time t _R reduced. As a result, the voltage Uss at the busbar could also increase suddenly, as according to the variant of 5 the case was. Here, however, an additional reactive power control is now performed, especially by an additional device. As a result, additional reactive power can be fed or provided here as Qz referred to as. Due to this additional reactive power Qz can This voltage jump of the voltage Uss are counteracted at the busbar.

In particular, such an additional reactive power control is performed here, which feeds reactive power exactly as much and in a corresponding manner, that the voltage Uss at the busbar is lowered by the active power P _WEA and in particular by the parallel lowering of the reactive power Q _WEA does not rise. This additional reactive power control counteracts so. The additional reactive power control can provide that the additional reactive power Qz after the reduction time t _R is gradually reduced again, especially with a decreasing ramp and accordingly reduced linearly. This then leads to a slow increase in the voltage Uss at the busbar, but this is so slow that a tapped transformer can counteract this. The voltage on the primary side 316 of the transformer 312 can thus be kept. As a result, the additional reactive power control can then be driven back to a value of 0, so that then no additional reactive power is fed.

The additional reactive power in the reactive power control can basically be provided by the inverters of the wind turbines. The control value can be added to a reactive power value of a phase angle control. The setpoint can be achieved, for example, by a central parking control, which is also called FCU can be referred to, or a remote control terminal, also called RTU are specified, whereas the phase angle is adjusted by a control or regulation of a wind turbine.

As further variants, it is proposed that a different wind energy installation or another wind farm, a STATCOM or other compensation mechanisms be used as an actuator for generating additional reactive power.

The disadvantage here may be particularly that such an additional reactive power control is complex.

For wind farms that are not directly connected to the busbar, it may be a conflict of interest if they must limit voltage changes both at the grid connection point and at the busbar.

In this case, it can be critical if the wind farm regulates the specification of a cos (φ) reactive power. A regulation of the reactive power can also be called regulation of the reactive power budget of the wind farm. A particularly critical case is when the reactive power control, especially the given power factor, ie cos (cp), does not fit or does not fit exactly enough to the system. In this case, a reactive power budget can also be taken into account if, for example, a network operator specifies a reactive power budget.

at 9 temporarily the voltage at the network connection point ( NVP ). This indirectly makes one more suitable for the network link point cos (φ) one, also as correct cos (cp) can be designated.

This can be done in the exemplary topology according to 3 have a major impact on the busbar voltage.

If the park, unlike the exemplary topology of 3 , is connected directly to the busbar, this leads in accordance with 9 proposed methods for special benefits.

9 shows a variant in which a scheme is used, the voltage U _NVP at the network connection point 304 regulates. For this purpose, it is also assumed here that the injected active power P _WEA at the time of reduction t _R is suddenly reduced. It is then but a scheme provided that the voltage U _NVP initially stops at the network connection point. This is the input reactive power Q _WEA at the time of reduction t _R lowered accordingly. Of the cos (cp) changes as a result. To the cos (cp) to get back to the previous value, then becomes shortly after the reduction time t _R the reactive power slowly ramped up to a setpoint, in particular linear, which corresponds to the initial cos (φ) specification or by which the cos (φ) is then realized.

By this measure, the voltage U _NVP initially held at the network connection point, but then also approximately ramped down, so particularly linear down to a later value, the voltage U _NVP at the network connection point then maintains, as soon as the previous cos (φ) was reached again. Of course, here could also be a new setpoint for the cos (φ) given, if this is desirable for other reasons.

At the same time, however, the voltage Uss at the busbar jumps through this measure at the time of reduction t _R at. But even then it is by the gradual linear change in the fed reactive power Q _WEA accordingly reduced again.

According to a variant, it is proposed to limit both jumps, ie the jump of the voltage USS at the busbar and the reactive power jump, to a predetermined extent. For this purpose, a small reactive power jump can be allowed in order to subsequently return the reactive power with a ramp. It can thereby be achieved that instead of a large jump in the voltage USS at the busbar, there occurs only a small jump, while at the network connection point also a small voltage jump is accepted. At these two points the tension jumps in different directions, but the jump splits up into two small jumps.

It should be noted, however, that the connection impedance 406 can also be completely different. Alternatively to the in 3 illustrated topology, the network connection point could be connected to the busbar without or without significant impedance, so for example. Without or only with negligible connection cable. In that case, the voltage Uss at the busbar would be equal to the voltage U _NVP Behavior at the network connection point, because the network connection point and busbar would be electrically equal or at least almost the same. Then, according to the voltage Uss at the busbar would not change abruptly, but only gradually, as in 9 also for the tension U _NVP is shown at the network connection point. Accordingly, a tapped transformer could counteract this gradual voltage drop.

In that regard, the illustrated 9 but that such a scheme for holding the voltage U _NVP is not always advisable at the network connection point, but depends on the specific situation, namely also on the transmission behavior from the network connection point to the busbar.

Claims (14)

Method for feeding electrical power into an electrical supply network by means of a decentralized feed unit, in particular by means of at least one wind turbine, wherein the supply unit is connected to a grid connection point for feeding in the electrical power, the network connection point is connected directly or via a connection connection with a transformer point, for transmitting the electrical power from the network connection point to the transformer point, possibly via the connection connection, - The transformer point is connected via a transformer to a network section, for transmitting the electrical power from the transformer point via the transformer to the network section, comprising the steps Feeding electrical real power into the electrical supply network at the grid connection point, Feeding electrical reactive power into the electrical supply network at the network connection point, detecting a change to be made in the active power to be fed in, - changing the injected active power according to the detected change to be made, and Limiting a time change of the fed reactive power when changing the fed active power and / or immediately thereafter to counteract a voltage increase at the transformer point and / or in the network section, and / or - Temporary activation of a voltage regulation as a function of changing the injected active power to perform during and / or immediately after changing the injected active power voltage regulation at a reference point, in particular at the network connection point to dynamically adjust the voltage at the reference point or network connection point, and / or along a trajectory, especially along a ramp. Method according to Claim 1 , characterized in that the limiting of the time change of the injected reactive power is such that - the fed reactive power according to a change function, in particular according to a ramp with a magnitude limited slope, is changed and / or - specified for the fed reactive power a gradient limit is, which specifies a maximum temporal change of the input reactive power according to the amount, in particular so that the fed reactive power is changed with a time gradient, which does not exceed the amount of the gradient limit. Method according to Claim 1 or 2 , characterized in that the transformer - has a primary side to which the transformer point is connected, - has a secondary side to which the network section is connected, and - the transformer is designed as a step transformer and can set a transmission ratio from the primary side to the secondary side, in order thereby to control a voltage level at the transformer point and / or at the network section, wherein - limiting the time change of the fed reactive power is such that a resulting from the change in the fed reactive power voltage change at the transformer point or on the primary side is so slow that the step transformer can compensate a resulting voltage change. Method according to one of the preceding claims, characterized in that no limitation of a temporal change is provided for the fed active power. Method according to one of the preceding claims, characterized in that the temporarily activated voltage regulation is active only when changing the injected active power and / or immediately thereafter and the voltage at the network connection point of a value that is changed by changing the injected active power, in whole or in part is attributed to a value that the voltage at the network connection point had immediately before changing the injected active power, wherein the temporarily activated voltage regulation is carried out in particular when the network connection point is directly connected to a transformer point. Method according to one of the preceding claims, characterized in that - for the supply of electrical reactive power, a power factor control (cos (φ) control) is provided in which the reactive power fed is adjusted in dependence of the fed active power so that a predetermined power factor ( cos (φ)), where - when changing the injected active power - the fed reactive power is initially changed at the same time so that the power factor remains unchanged, - a new value for the power factor then in response to a change in the active power and Reactive power changing voltage or expected voltage is specified at the grid connection point and - the power factor is returned to the predetermined power factor, the feedback is delayed and / or carried out over a time function. Method according to one of the preceding claims, characterized in that - for the supply of electrical reactive power, a power factor control (cos (φ) control) is provided in which the reactive power fed is adjusted in dependence of the fed active power so that a predetermined power factor ( cos (φ)), where - when changing the injected active power it is changed along a ramp or trajectory, - when changing the applied active power along the ramp or trajectory voltage regulation is used to keep the voltage at the reference point constant, at least to counteract a voltage change by changing the injected active power, the voltage control sets the reactive power and the power factor control (cos (φ) control) is disabled during this voltage regulation, - after the change of the fed active power a blind power value resulting from the voltage regulation is performed on a new reactive power value, which would result from the deactivated power factor control (cos (φ) control), wherein - the reactive power value is guided in particular via a ramp and / or trajectory to the new reactive power value, and - the deactivated power factor control (cos (φ) control) is activated as soon as the reactive power value has reached the new reactive power value. Method according to one of the preceding claims, characterized in that - changing the injected active power is performed via a real power jump, whereas - changing the reactive power over a time function, in particular via a ramp function is performed. Method according to one of the preceding claims, characterized in that the limitation of the temporal change of the fed reactive power of the type and / or size of the connection connection is dependent. A wind turbine for feeding electrical power into an electrical supply network wherein - the wind turbine for feeding the electric power is connected to a network connection point, - the network connection point is connected directly or via a connection connection with a transformer point, for transmitting the electrical power from the network connection point via the connection connection the transformer point, - the transformer point is connected via a transformer to a network section, for transmitting the electrical power from the transformer point via the transformer to the grid section, and the wind turbine comprises - an inverter for feeding active electrical power into the electrical grid at the grid connection point, - Inverter control for controlling a supply of reactive electrical power to the electrical supply network at the grid connection point, an input interface for detecting a change in the active power to be fed in, wherein - the inverter controller is prepared to change the applied active power according to the detected change to be made, and wherein - the inverter controller is prepared to control or limit a time change of the supplied reactive power when changing the supplied one Active power and / or immediately thereafter to counteract a voltage increase at the transformer point and / or in the network section and / or wherein - the inverter control is prepared to perform a temporary activation of a voltage regulation as a function of changing the injected active power to during and / or immediately after changing the fed active power to perform a voltage control at a reference point, in particular at the network connection point to the voltage at the reference point or Netzv dynamically align point and / or along a trajectory, in particular along a ramp. Wind turbine after Claim 10 , characterized in that the wind energy plant, in particular the inverter control, is prepared to a method according to one of Claims 1 to 9 perform. Wind farm comprising several wind turbines, where - wind turbine after Claim 9 or 10 be used, and / or - the wind farm is prepared to a method according to one of Claims 1 to 9 perform. Feed-in arrangement for feeding electrical power into an electrical supply network, comprising a decentralized supply unit, in particular a wind turbine, - a network connection point, and - A transformer with a transformer point, where the feed unit is connected to the grid connection point for feeding in the electrical power, the network connection point is connected directly or via a connection connection with the transformer point, for transmitting the electrical power from the network connection point via the connection connection to the transformer point, - The transformer point is connected via the transformer to a network section, for transmitting the electrical power from the transformer point via the transformer to the network section, and the feed arrangement comprises an inverter for feeding active electrical power into the electrical supply network at the grid connection point, an inverter controller for controlling a supply of reactive electric power to the electric utility network at the grid connection point, - An input interface for detecting a change to be made in the active power to be fed, wherein - The inverter control is prepared for changing the fed active power according to the detected, to be performed change, and wherein - The inverter control is prepared for limiting a change over time of the supplied reactive power when changing the injected active power and / or immediately thereafter to counteract a voltage increase at the transformer point and / or in the network section, and / or the inverter control is prepared to carry out a temporary activation of a voltage regulation as a function of the change in the injected active power in order to carry out a voltage regulation at a reference point, in particular at the network connection point, during and / or immediately after changing the fed active power. Dynamically correct network link point and / or to guide along a trajectory, in particular along a ramp. Feed arrangement according to Claim 13 , characterized in that the feed arrangement, in particular the inverter control, is prepared for carrying out a method according to one of the Claims 1 to 9 - as a feed unit to a wind turbine after Claim 10 or 11 has, and / or - as a feed unit after a wind farm Claim 12 having.

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